All the guns in this film were supplied by Aldo Uberti Inc. of Italy.
A Fistful of Dollars (1964). It should be noted that Clint is seen armed with a Colt 1860 Army on this cover, yet never uses one throughout the Leone series.
Joe (Clint Eastwood), aka "The Man With No Name" uses a Single Action Army 5 1/2" Artillery with a color case hardened frame as his weapon of choice in the film. The infamous "Silver Rattlesnake Grips" were first seen in another show of his, Rawhide (1959), in which an outlaw used the same SAA and his character, Rowdy Yates, killed him and took the gun for himself.
Multiple other characters are also seen using SAAs.
Ramón can also be seen using a Winchester 1894 in some scenes, taking the place of his Winchester '92 rifle. Some nameless thugs are also seen armed with '94 rifles as well.
Ramón uses an Mitrailleuse Machine Gun to mow down soldiers during the meeting. It is a cross between a Mitrailleuse and a Maxim gun, but it is meant to imitate a Mitrailleuse machine gun which was in use in French army in 1860s and 1870s.
Contrary to the popular belief, this is not the same gun that was used in Django, as evidenced by muzzle end. This prop has way more number of holes in muzzle end than one used by Franco Nero.
Some of the soldiers at the meeting are armed with Mauser 1895 rifles, which are anachronistic to the film.
Unless the film is set in 1895 or later, Mexico was pretty lawless into the 20th century.
A 12 Gauge Double Barreled Shotgun is seen several times in the film, most notably used by a Rojo thug to try to shoot Joe after he defeats Ramón, before he is killed by the bartender, Silvanito (José Calvo), who is also using a side-by-side shotgun.
